UN report says crossing the 1.5C warming threshold is inevitable

The world is now certain to exceed the 1.5C warming threshold, but decisions made today will determine whether the overshoot is temporary or permanent, Yle reports, citing the UN Environment Programme’s annual emissions report.

Decades of inadequate climate action have put the world on a path beyond 1.5C of warming, the report says. However, it remains possible to limit peak warming to 1.7C or 1.8C, UNEP chief Inger Andersen said.

Every fraction of a degree and every additional year above 1.5C increases the risk of irreversible changes, including melting glaciers, carbon released from permafrost, disruption to ocean circulation such as the AMOC, and the destruction of coral ecosystems.

Warming also has devastating consequences for people. Floods in Nepal killed about 1,500 people in August, according to confirmed figures, and left thousands missing. The changing climate is destabilising the Himalayan ecosystem, melting permafrost and glaciers, and increasing risks, the report says.

Countries must now work not only to keep warming well below 2C, but also to minimise how far and for how long temperatures exceed 1.5C. UNEP says they should also establish a credible plan to return to 1.5C by the end of the century.

The report’s scenario for limiting the overshoot as much as possible requires strict emissions cuts to start in 2025. Based on last year’s emissions and climate plans, it would limit peak warming to 1.7C to 1.8C with a 66 percent probability, and give the world about a 50 percent chance of returning to 1.5C or below by 2100. The scenario remains consistent with the Paris Agreement’s goal of keeping warming well below 2C while pursuing efforts to limit it to 1.5C.

To achieve that, global greenhouse gas emissions would need to fall 18 percent by 2030, 45 percent by 2035 and 69 percent by 2040, compared with 2025 levels.

Two-thirds of countries have submitted new emissions reduction pledges for the international climate summit beginning next month. If implemented, the pledges would cut global emissions by 5 to 8 percent by 2030 and 11 to 15 percent by 2035, relative to 2025 levels. Those reductions fall far short of what is needed, Andersen said.

The report says there is significant potential to accelerate emissions cuts. Global deployment of solar and wind power has consistently exceeded even the most optimistic forecasts since the Paris Agreement was adopted. Growth in fossil fuels has been slower than forecasts made a decade ago, but remains too high, while deforestation has not been curbed sufficiently.

Renewable energy and climate action have already reduced emissions around the world, but much more is needed, the report says. “Nations must understand that the return to low emissions starts now. Not later, but now,” Andersen said, calling for rapid, deep and sustained cuts.